Overview of Open-pit Mining in Yanjin Mine—Application of Air Medium Uncoupling Mixed Charge Structure

Deep gold mine bench blasting cartridge in open pit mining, the medium was air mixed study drug junction uncoupling. After nearly 500 holes in 65 test blasting areas, the blasting quality is good and the unit consumption of explosives is significantly reduced. The application of this technology plays an important role in improving blasting efficiency, reducing blasting cost and reducing vibration intensity.

I. Overview

Gold ore mainly on the type of the cartridge are: pyrite phyllic cataclasite phyllic post cracking mineral matter, phyllic granite, hard metal ore explosive type, f = coefficient Platts 3 to 8. The annual mining and stripping volume of the mine is 4.6 million tons, and the working steps are 5. The perforation uses KQ150 and YQ150 down-the-hole drilling rigs . The drilling efficiency is 2500~3500m/month, the design step height is 12m, and the slope angle is 68°.

Second, the experimental research content

The warehouse blasting of Cangshang Gold Mine mainly uses emulsified explosives. More than 80% of them are water holes, and the water depth is 0~2m. The plastic detonating tube is used for non-electric detonation system. Two detonation points are set for each hole, and the differential blasting technology is used. Slash blasting method.

The main purpose of the experimental study is to reduce the unit consumption of explosives, reduce the large roots and weaken the vibration of the mining area, and improve the blasting effect by changing the previous continuous column charge to the air medium without coupling the mixed structure.

It has been proved at home and abroad that air can improve the matching relationship of blasting energy in the process of transmission, reduce the initial explosion pressure, adjust the pulse coefficient of the explosion to reduce the initial peak of the explosion pulse, prolong the duration of the explosion pulse, and improve the energy utilization rate of the explosive. In the process of step blasting, the reasonable use of air space, so that part of the energy stored in the air medium, can increase the blasting time of the entire blasthole, increase the tensile impulse, so that the distribution of energy along the blasthole tends to be uniform, therefore, can reduce blasting The crushing zone expands the crushing zone, reduces the blasting vibration intensity, changes the energy distribution, fully utilizes the explosive energy, and improves the blasting effect.

Third, the test method

The process of the air medium not coupling the mixed drug structure is: selecting an emulsified oil powder roll (coupling) of 1.5 to 2.5 m height according to the height of the water hole, and then loading the special pharmaceutical roll (not coupled) to a certain height, at the top Pack 1 to 2 emulsified oil rolls (coupling), and finally fill with slag. The charge structure is shown in Figure 1.

Figure 1 Schematic diagram of the air medium charge structure

1, 4 - floating fried medicine; 2 - air medium; 3 - special pharmaceutical volume; 5 - filling; 6 - detonating tube.

(1) Determining the special pharmaceutical volume: the medicine roll is 0.85m long and the medicine diameter is 78mm. The outer packaging is a plastic broken cylinder. There is a coupling thread between the cylinders, which can be continuously charged. One end of the plastic shell can be inserted into a detonating tube. The coupling coefficient was determined to be 1.9 to 2.2, and the main component of the explosive in the drug roll was No. 2 rock ammonium strontium explosive.

(2) Statistics and calibration of blasting effects. In the same explosion zone, the continuous column charge hole and the air medium are respectively arranged without the mixed drug hole for comparison, and the pre-explosion pre-crush condition, the base and the block rate, the loading efficiency, the blasting material consumption, etc. are counted. The DSVM-1(A) vibrometer measures vibration intensity.

Fourth, the analysis of blasting effect

The relevant data obtained from the 65 test explosion areas are summarized as shown in Table 1.

Table 1 Test explosion zone system calibration data table

It can be seen from Table 1 that the air-mediated uncoupling mixture is more continuous than the columnar coupling charge, and the single consumption of the explosive is significantly reduced. The explosive consumption of the three rocks is reduced by 26%, 32%, and 26%, respectively; The magnitude of the explosives in the three types of rock is reduced by 37%, 46%, and 37% respectively: through testing, the seismic velocity in the far zone is reduced by 21% to 30%, which is stable to the slope of the stope and 200m in the dangerous area. Equipment and residential areas have played a very good role in protection.